Optical communication techniques, capable of transferring large-volume information at high speed, are already put into practical use for long-distance trunk communication systems.
Also, such techniques are developed that connect a plurality of computers by optical fibers and connects wiring boards inside a computer by optical fibers. In these techniques, optical signals are converted into electric signals by optical devices such as optical transceivers connected to optical fibers.
Optical devices are provided with optical waveguides for transferring optical signals. A device which allows an optical waveguide to branch into a plurality of optical paths is called an optical branching waveguide. By utilizing the optical branching waveguide, variations of optical paths can be increased.
However, an optical branching waveguide which can easily allow an optical path to branch is not developed.
Note that the techniques related to the present application are disclosed in the following documents:
Japanese Laid-open Patent Publication No. 10-186153;
Japanese Laid-open Patent Publication No. 63-70219;
Japanese Laid-open Patent Publication No. 2012-181433;
Japanese Laid-open Patent Publication No. 2011-191647;
International Patent Publication no. WO2016/052343; and
Luxtera Inc., “Light source approach for silicon photonics transceivers”, searched on Nov. 8, 2016 by the internet.